Hg-0 adsorption experiments with different kinds of activated carbons (ACs) were conducted in nitrogen environment to study the effects of ACs with different surface characteristics on adsorption. Three kinds of ACs prepared by steam activation did not adsorb elemental mercury (Hg-0) in nitrogen environment, while another kind of AC prepared by chemical activation using zinc chloride (ZnCl2) showed significant Hg-0 adsorption capability in the same experimental conditions because Hg-0 was oxidized by the oxidative elements on the surface of AC. ACs without oxidative elements did not adsorb Hg-0 through physical adsorption in nitrogen environment. it was therefore concluded that Hg-0 adsorption by AC was a chemical adsorption process. (C) 2009 Elsevier B.V. All rights reserved.